A portable apparatus and method for cutting linear trenches in a concrete ground surface includes two bars extending in parallel spaced relation along the concrete with an elongated track removably fastened and extending orthogonally thereto. A trolley supporting a motor-driven cutting wheel is movably engaged with the track. A depth adjuster alternately lowers and raises the cutting wheel to engage and disengage the concrete while the trolley follows contours of the concrete to cut a kerf of uniform depth. The track is selectively movable to spaced locations along the lengths of the two bars to cut a first plurality of parallel kerfs in a first direction. The apparatus is rotatable about a vertical axis to cut a second plurality of parallel kerfs oriented in a second direction at a predetermined angle, e.g., 90 degrees, to the first direction, to form a simulated tile pattern in the concrete.